Search: Elasticsearch-style highlighted match snippets (results + typeahead)

- SearchHighlight.Snippet: extracts a ±70-char window around the first
  matching term and marks it (with ellipses) — the ES "highlight" fragment.
- Result cards (shift/job/talent) now show that snippet from the matched
  description/tags when a query is present, so you SEE where the term hit
  (e.g. «…دارای مدرک <mark>mmt</mark>…») instead of just the role.
- Typeahead suggestions gain a highlighted "sub" line (talent→tags,
  shift→city·specialty, job→facility·city) so matches show in the dropdown too.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/JobsMedical.Web/Pages/Shared/_Layout.cshtml

@@ -259,8 +259,10 @@
                     .then(function (items) {
                         if (!items || !items.length) { hide(); return; }
                         var html = items.map(function (it) {
+                            var sub = it.sub ? '<span class="ns-sub">' + hi(it.sub, q) + '</span>' : '';
                             return '<a href="' + it.url + '"><span class="ns-type">' + esc(it.type) +
-                                '</span><span class="ns-label">' + hi(it.label, q) + '</span></a>';
+                                '</span><span class="ns-text"><span class="ns-label">' + hi(it.label, q) +
+                                '</span>' + sub + '</span></a>';
                         }).join('');
                         html += '<a class="ns-all" href="/Search?Q=' + encodeURIComponent(q) + '">همه نتایج برای «' + esc(q) + '» ←</a>';
                         box.innerHTML = html;